Field of the Invention
The present invention relates to a parking lock-releasing device for a vehicle in which a parking mechanism actuated by an electric or hydraulic actuator unrotatably locks an output shaft of a transmission when a shift range is switched to a parking range. The lock-releasing device is for manually releasing the locking by the parking mechanism when the actuator is in an inoperable state with the shift range having been switched to the parking range.
Description of the Related Art
Conventionally, as a parking lock-releasing device for a vehicle, there has been proposed one disclosed in Japanese Patent No. 5008616 filed by the present applicant and has already been allowed. The vehicle having the parking lock-releasing device includes a shift lever that is operated when the shift range is switched, an actuator for actuating a transmission according to the operation of the shift lever, and a controller that is disposed between the shift lever and the actuator for transmitting and receiving electrical signals to and from the shift lever and the actuator to control the transmission. The vehicle has a so-called shift-by-wire system applied thereto for switching the shift range via a communication line. When the shift lever is operated by a driver of the vehicle, an electrical signal corresponding to the operation of the shift lever is transmitted to the actuator via the controller, and the actuator switches the transmission to a desired range.
In the vehicle to which is applied the shift-by-wire system, there is a fear that when the actuator becomes inoperable due to battery exhaustion which makes it impossible to supply power to the actuator or due to a failure of the actuator itself, the shift range of the transmission becomes incapable of being switched. In particular, when the shift range is in the parking range, normally, the output shaft of the transmission has been unrotatably locked (subjected to parking lock) by the parking mechanism, and hence it is impossible to move the vehicle in spite of an attempt to move the vehicle e.g. by traction. To cope with this inconvenience, the vehicle as described above is provided with a parking lock-releasing device for manually releasing the locking by the parking mechanism.
The parking lock-releasing device includes an long slender cylindrical outer casing, an inner cable which is slidably accommodated in the outer casing and has one end connected to the shift lever of the transmission and the other end (hereinafter referred to as “the front end”) positioned at or close to an end (front end) of the outer casing on a side remote from the transmission, and a cap which is provided at the front end of the outer casing for water-tightly sealing the front end at normal times and is connected to the front end of the inner cable when the parking lock is released. The front end of the outer casing is provided with an outer casing terminal member (hereinafter referred to as “the outer terminal member”) which is formed in a hollow cylindrical shape for having the front end of the inner cable inserted therein and has a female screw on an inner peripheral surface thereof. On the other hand, the front end of the inner cable is provided with an inner cable terminal member (hereinafter referred to as “the inner terminal member”) which is formed in a columnar shape and has a male screw on an outer peripheral surface thereof. Further, the cap is formed in a hollow shape which extends like a bar over a predetermined length and has one end which is open. The one end has a male screw formed on an outer peripheral surface thereof for screwing into the female screw of the outer terminal member, and the other end of the cap has a female screw formed thereon which can be screwed onto the male screw of the inner terminal member. Therefore, at normal times, the cap is connected to the inner cable in a state screwed into the outer terminal member, whereby water is prevented from entering the interior of the outer casing so as to prevent the inner cable from suffering from rust and like damage. Further, the inner terminal member of the front end is slidable within the cap along with sliding of the inner cable when the shift range is switched by the actuator. Note that a front end of the cap which is the above-mentioned other end has a cover removably mounted thereon for preventing the female screw from suffering from rust and like damage.
In the lock releasing device constructed as above, the locking by the parking mechanism is released as follows. First, the cover is removed from the front end of the cap, and the cap is rotated in a predetermined direction and is thereby removed from the outer terminal member. This opens the front end of the outer terminal member to thereby expose the inner terminal member as the front end of the inner cable to the outside. Next, the cap is reversed, and the female screw of the front end thereof is screwed onto the male screw of the inner terminal member, whereby the cap is connected to the inner terminal member in a state screwed thereon. Then, the cap is pulled by a predetermined stroke, whereby the shift lever of the transmission is actuated via the inner cable to thereby release the parking lock.
As described above, in the conventional lock releasing device, when releasing the lock, the operator has to remove the cap from the outer terminal member by rotating the cap, and further, after reversing the cap, screw the cap onto the inner terminal member to thereby connect the former to the latter. These operations before pulling the inner cable to release the parking lock are troublesome. Further, the parking mechanism is generally configured to operate in a locking direction by the urging force of a spring or the like, and hence the operator needs to hold the inner cable in a pulled state to maintain the locking by the parking mechanism in a released state. That is, the operator has to hold the cap in the state pulled by the predetermined stroke against the urging force of the parking mechanism, and if the operator releases the hand from the cap, the locking by the parking mechanism is performed again. Thus, the above-described lock releasing device leaves room for improvement in workability in releasing the locking by the parking mechanism.